The Marmertine prison, begun by Ancus Martius, and completed by Servius Tullius, yet remains nearly perfect, and is a good example of primitive masonry. In the time of the Republic, the Appian road, used to this day, was commenced by Appius Claudius Cæcus. The Forums of Julius Cæsar, of Augustus, of Nerva, and of Trajan, were adorned by many of the noblest structures in Rome. But the most useful works were exterior to the city, such as those wonderful engineering structures, the aqueducts. Of these, the Appian, Martian, and Claudian were most celebrated. The last-mentioned, completed by the emperor Claudius, A.D. 51, and yet in existence, is forty-six miles in length; for thirty-six, it runs under ground; and a series of lofty arches, six miles in length, forms a noble feature in the Campagna, still supplying the city with pure water. That commenced by Quintus Martius, B.C. 145, was also an astonishing undertaking, upwards of sixty miles in length, comprising three separate channels conveying water from different sources, and partly carried on an arcade of seven thousand arches, seventy feet in height. Neither were these colossal works confined to the seat of empire alone, but were executed in the remoter West as well, as at Segovia, Metz, and Nimes. As one sees this vast supply of pure water still poured from the Sabine hills through the ancient aqueducts, he feels how superior were the republican contributions to the true greatness of Rome, compared with all the imperial and later works. It should be particularly observed that the Romans emulated only the pictorial half of Greek design; and this they greatly increased, regarding the refinements of propriety as virtues too insipid to be admired. They were evidently pleased with the columnar ordinance of a Greek temple, but had no affinity with the instinctive sense of propriety so prominent in Athenian architects, and could not understand the true purpose of a colonnade. They did not look at pillars, entablatures, and pediments as expressions, but simply as physical substances, which in their combinations formed a picturesque object, which could be used in a scenic display of sensual magnificence. Impelled by an insane passion for decoration, the architects of the Augustan age emblazoned the imperial city with a thousand monumental errors which in due time subsided into effete grossness, and became the compost to nourish an entirely new and superior type of art. Such is the wisdom and goodness of Providence!